TITAN XD LOW FUEL PRESSURE
QUESTION: I have a ’16 Nissan Titan XD diesel with 36,900 miles on it. I do a lot of towing, and on a few occasions (when the fuel-range indicator drops below 65 miles remaining), a “Low Fuel Pressure” warning displays. Nothing changes in driveability, but the first time it happened it definitely caught my attention. After filling up, the warning goes away, and it doesn’t appear again until the driving range hits that 60- to 65-mile mark. Is there a problem with the fuel system or the tank? I follow the owner’s manual for all the maintenance. With only a 26-gallon tank and 10 mpg when towing, this is becoming a range issue for me. ANSWER: The CP4 injection pumps on new diesel engines are very finicky about being starved of fuel. They’re prone to failure in low-fuel conditions, and this is costly because correcting the damage usually requires replacing the entire fuel system. The “Low Fuel Pressure” and “Low Fuel” warnings are Cummins’ way of ensuring the driver is very aware the fuel level is nearing a point of concern and that he or she has adequate time to refuel—much like diesel-exhaust-fluid warnings. When the fuel level gets below a quarter tank, the ECM triggers those warnings. It will also send the same alert when there’s a fuel-pressure drop due to debris getting into the pick-up in the tank or if there’s restriction farther upstream in the two filters in the low-pressure side of the fuel system. If the “Low Fuel Pressure” warning comes on before a quarter of a tank, there could be a pressure-sensor issue, contaminated fuel, bad fuel- filter O-ring, clogged fuel filters, a filter that has a failed check valve, a lift pump dying, or low voltage to the fuel pump. These are all items a dealership service department should check while the truck is still under warranty. If you want to extend the driving range of the stock fuel tank, you might consider installing a Sinister Diesel fuel-tank sump, which draws from the bottom of the tank. A better choice is to replace the stock mid-ship fuel tank with a high-capacity version such as the 50-gallon offerings from Transfer Flow or Titan Fuel Tanks. Either one will nearly double your current driving range.
Nissan Titan XD diesels will warn the driver the fuel level is low when the miles-to-empty indicator reads 60 to 65 miles, usually triggering a “Low Fuel Pressure” warning that will hopefully assist the driver in not running out of fuel (which can damage the CP4 injection pump and fuel system).